QUETTA, PAKISTAN—Gunmen opened fire on Pakistani police escorting a Spanish cyclist through a volatile province Wednesday, killing six officers, while a bomb targeting a polio vaccination team killed seven people in the northwest.

The attacks in two different parts of the country left many questioning whether the government has a plan to tackle the country’s stubborn militancy problem.

Radical Sunni Islamic militants have stepped up attacks against members of the minority Shiite Muslim sect in recent years, and violence has been especially bad in the impoverished southwestern province of Baluchistan.

On Wednesday, gunmen opened fire at a group of police escorting a Spanish cyclist in Baluchistan, killing six police officers and wounding the cyclist. Police official Mohammad Ibrahim said nine officers were also wounded in the shooting.

Ibrahim said more than a dozen tribal policemen were escorting the Spanish cyclist, who was travelling from Iran to Pakistan. The cyclist’s name was not immediately available.

No one claimed responsibility for the attack but Ibrahim said he suspected the same sectarian group that targeted a group of Shiite pilgrims returning from Iran on Tuesday was responsible for the Wednesday incident.

Police had said 20 people died when a bomb exploded near the pilgrims’ bus, but local police official Asad Cheema said the death toll had risen to 28. Some of the wounded were still listed in critical condition.

Shiite Muslims rallied Wednesday in Quetta, the capital of Baluchistan, demanding action to stop the continued violence against their sect.

“We will not bury our dear ones until the government acts against the attackers,” local Shiite leader Agha Dawood said.

In the northwest, a bomb rigged to a bicycle exploded next to a police patrol on its way to guard a polio vaccination team. Six officers were killed as well as a boy who was nearby, said officer Shafiullah Khan.

The blast happened in the Charsadda district, just outside the provincial capital of Peshawar. The bomb also wounded 11 people, four of them tribal policemen, Khan said.

It was the second such attack in the past 24 hours. On Tuesday, gunmen killed three health workers in an attack on a polio vaccination team in the southern port city of Karachi.